The present invention relates to a semiconductor device and a method for fabricating the same. More specifically, the present invention is related to a semiconductor device and a method of fabrication applying a so-called multi-chip module technology, in which a plurality of semiconductor chips is assembled as a single electronic component.
In order to respond to demands like downsizing and small energy consumption, a mounting technology in which semiconductor elements are assembled under high density is implemented, along with high integration technology of such semiconductor elements. In order to realize a further higher density assembly, among such mounting technologies, a multi-chip module (herein after referred to as MCM) technology carrying multi-chip semiconductor elements (a semiconductor chip) on a same supporting substrate as one single electronic component beforehand has been developed. Such MCM technology achieves substantial multi-functionality by assembling two or more semiconductor chips on one single base.
FIG. 7 is a plane view and an A–A′ sectional view that shows one example of a conventional semiconductor device using such MCM technology. The semiconductor device shown in these figures has two semiconductor chips 102 and 103 having different functions, mounted on a supporting substrate 101. On the supporting substrate 101, multi-chip electrode pads 104 (illustrated only in the plane view) and wiring (not shown on the figures) to interconnect these electrode pads 104 are formed. In addition, each semiconductor chips 102 and 103 are interconnected by means of an electrode pad provided on the surface of the supporting substrate 101 and wiring (not shown on the figures), as well as a wire 105. Still, connection of such semiconductor device with an outside device is done through the electrode pad 104 provided on the supporting substrate 101.
In addition, in Japanese Patent Laid-Open No. Hei5-47856, there is disclosed a semiconductor device comprising: an insulation film formed as to cover plural semiconductor chips mounted on a supporting substrate (a package of ceramic circuit boards or the like); connection holes reaching the semiconductor chips and the supporting substrate on the insulation film; and wiring formed on the insulation film to connect electrode pads on the supporting substrate to the semiconductor chips through these connection holes. According to such semiconductor device, connection of the semiconductor chips to a package does not rely on wires, but on wiring formed on the insulation film covering the semiconductor chips so that it is possible to increase a number of leads taken out from the semiconductor chips, at the same time the semiconductor chips and the pads on the supporting substrate are connected by the shortest distance. In addition, a semiconductor device of a construction having inner path holes within the insulation film has been proposed in order to realize multi level interconnection.
Furthermore, in Japanese Patent Laid-Open No. Hei9-64269, there is disclosed a semiconductor device that reduces a capacity of each output buffer of plural semiconductor chips by establishing an output buffer distributing the capacity of each output buffer, to then realize downsizing of each semiconductor chip.
Other than a semiconductor device of MCM type such as described above, there is also realized a high capacity semiconductor device by making a system LSI in which the functions of plural semiconductor chips are fabricated in one single semiconductor chip.
However, regarding the semiconductor device of MCM type described above, as there are interconnections between semiconductor chips and connections of a semiconductor chip with an outside device by means of electrode pads on the supporting substrate (for example, a ceramic circuit board) on which the semiconductor chips are mounted, an area on the supporting substrate for placing the electrode pads and the wiring is required in addition to an area to implement the semiconductor chips. This, along with increasing a substantial implementation area, becomes also a factor of raising the cost of the semiconductor device.
In addition, the semiconductor device of MCM type has higher power consumption as plural semiconductor chips are sealed as one unit within a resin film or layer, thus causing generation of heat in correspondence with such power consumption. For this reason, such heating causes, in addition to causing failure in the function of the element itself formed in the semiconductor chip, the semiconductor chips unstick due to a difference in thermal expansion coefficient between the supporting substrate and the semiconductor chips, and further causing a problem of generating cracks in the resin that seals the semiconductor device.
On the other hand, in a system LSI type semiconductor device, as plural functions (memory and logic, for example) are made within one single semiconductor chip, the design process and the wafer process becomes complex, the yield decreases, the fabrication cost increases and, furthermore, the TAT (Turn Around Time) is prolonged, as compared to a semiconductor device of MCM type.